Acute

Viral infection

Norovirus, rotavirus

Bacterial infection

Salmonella, Campylobacter, or Shigella species; Escherichia coli; Clostridioides difficile (formerly Clostridium difficile)

Parasitic infection

Giardia species, Entamoeba histolytica, Cryptosporidia species

Food poisoning

Staphylococci, Bacillus cereus, Clostridium perfringens

Drugs

Chronic

Drugs

See Acute (above)

Functional

Irritable bowel syndrome, functional diarrhea

Dietary factors

See table: Dietary Factors That May Worsen Diarrhea

Inflammatory bowel disease

Ulcerative colitis, Crohn disease

Surgery

Intestinal or gastric bypass or resection

Malabsorption syndromes

Celiac disease, pancreatic insufficiency

Carbohydrate intolerance (particularly lactose intolerance)

Small intestinal bacterial overgrowth (SIBO)

Tumors

Colon carcinoma, lymphoma, villous adenoma of the colon

Endocrine tumors

Vipoma, gastrinoma, carcinoid tumors, mastocytosis, medullary carcinoma of the thyroid

Endocrine

Hyperthyroidism

Diabetes (multifactorial concurrent celiac disease, pancreatic insufficiency, autonomic neuropathy)